SB 9 vs. an ADU: Which Path Fits Your Lot?
Carlos Moreno, Assoc. AIA
Founder, KĒĒP
Published August 12, 2026 · Updated August 24, 2026 · 6 min read
The short answer
SB 9 and ADUs solve different problems. An ADU adds a separate home on your existing lot, which you keep whole — simpler, faster, and cheaper to permit. SB 9 lets eligible homeowners split their lot into two parcels and build up to two units each, aimed at creating separately sellable land. For most families who want space for relatives or rental income, an ADU is the better fit.
What each one gives you
The clearest way to choose is to name what you actually want out of the property.
| ADU | SB 9 lot split | |
|---|---|---|
| Keeps your lot whole | Yes | No — creates two parcels |
| Main goal | Add living space or rental income | Create separately sellable land |
| Typical cost & complexity | Lower, more predictable | Higher — survey, legal, utilities |
| Permitting | Ministerial, often 4–7 months | More involved, city-specific |
| Owner-occupancy | Not required for new ADUs | Often required for the split |
If your goal is a home for a parent or adult child, rental income, or added property value while keeping your land intact, an ADU is almost always the right tool. SB 9 makes sense in a narrower case: when you specifically want to divide the land into parcels that could be sold apart.
Not sure which path fits your lot?
Get a free feasibility reportWhy an ADU is the simpler starting point
SB 9 sounds powerful — two parcels, up to four units — but the complexity is real. A lot split can require surveying, new legal descriptions, separate utility connections, and an owner-occupancy commitment, and cities apply their own objective standards on top. Some of SB 9's provisions have also faced legal challenges, which adds uncertainty.
An ADU, by contrast, is designed to be approved ministerially against clear standards, on the lot you already have. That's why we usually steer families toward the ADU first and only raise SB 9 when the specific goal is dividing the property.
Laws in this area change and are interpreted differently by city. Confirm current rules with your planning department or an attorney, or let a feasibility assessment map your options.
Common questions
SB 9 is a state law that lets eligible single-family homeowners split their lot into two parcels and build up to two units on each, subject to conditions. It is aimed at creating separately sellable parcels, not just extra living space.